Hello Speedskater
Well you inspire me something when mentionning Earth point connection.
Look at my ground schematic on my Post#6.
The earth point coming from main power connector splits in two cables and each ones go to individual MainPSU's where they have contact for coupling with Audio-ground.
From there the earth points on each MainPSU split on two individual wires to connect together on a chassis point for final chassis grounding.
The question : Could there be a problem by connecting to Audio-Gnd before chassis?
Luke
You have some other problem then.
Is your amplifier quiet without anything plugged in on the inputs?
Hello Bonsai
Each channel are perfectly quiet when nothing is plugged in.
I would suggest you reading my posts#5 & 8 to have a good state of my problem.
As soon as I connect channels together in parallel noise arrises gradually as I connect more channels together.
Anyway read these and you'll have a basic picture.
Luke
Speedskater
I forgot to say I'll read your section 5.8 tomorrow.
I jsu have to split now.
Thanks.
Luke
If things got burnt, your assy has got some issue.
Good way of connecting the input ground is to short all the grounds near the connector.
In my amp, that has different PSUs, I have used only one star ground, at the main psu(of high current). Grounds from other PSUs is connected to this star and every load gets connected to this star. I have absolutely no problem, but my amp is stereo.
Gajanan Phadte
Good way of connecting the input ground is to short all the grounds near the connector.
In my amp, that has different PSUs, I have used only one star ground, at the main psu(of high current). Grounds from other PSUs is connected to this star and every load gets connected to this star. I have absolutely no problem, but my amp is stereo.
Gajanan Phadte
Then explain why the smoke come out. You have connected only points that should be at the same potential (at least reading your drawing).
If it were my amp, my next move would be to understand why the smoke came out when anything bad should not have to happen.
Some people want to learn from mistakes but not everybody can...so...
When you have an answer to this question, you will probably find the solution to your problem.
Sesebe
Hello Gajanan
Here is the photo below.
By the way, my very first amp. With some experience, the other will be much improved.
From the Neutrik 6 pins connector one can see the three Canare L-2B2AT two conductors wires going to each of the three circuits from one of the two channels.
One of conductor is hot and the other conductor+shield is on Gnd.
Anything else wanted?...Just ask!
Thanks!
Luke
An externally hosted image should be here but it was not working when we last tested it.
Yes you may be right.
I'll have to figure out why smoke happened.
But two PCB from same two coils of XFO, two other coils from same XFO for one separate RegPSU board...three Star points coupled together, each referenced by floating sources...
0.000Vdc and very very low Vac between any each of them.
I bet I will learn something today!
OK now where do I start!
Luke
Last edited:
Hello Bonsai
Thanks for the kind words, even thought I find it a bit messy, especially when it's time to service it!
When I first started this project nine months ago I definitely underestimated the space needed to house everything as project showed nice possibilities and...problems to be solved.
I thought one MainPSU board was enough but I had to install a pair to fit everything, one for each channel which explains why there are two MainPSU boards.
I decided to have a higher Vdc for input section so ..here goes another PCB for RegPSU. with Vdc+/Vdc- Regs for each channel.
To make possible this new board I had to "roll" a new pair of coils on the transformer.
To have a lower magnetisation on core on XFO I had to roll again...so two new small coils to add on the primaries.
During planning of the Amplifier's BOM parts needed I had to work hard to figure out the complete information mess that came with these kit PCBs that I ordered.
I also had to modify these Amp's boards to suit new design and go around some limitations, reconfigure thermal management because different bias levels.
I haven't figured out "thumps" during power-ons so here goes another board for Relays section.
Above all this, "your slave" MUST finish what he statred because he spent mucho amount of hours!
Anyway...thanks everybody for helping me, so please keep supporting me!
Right now I'm reading 5.8 section of Speedskater's AES Paper.
Suicide is not an option right now!
Luke
Hello
An observation to show.
First I built a cable adapter which uses a pair of the matching Neutrik male connectors to fit into the actual amp.
On each connector pins 1,3 & 5 which are negatives or Gnd contacts are all connected together.
And the two connectors are connected together by these common connections.
That means six grounds brought together but the six signal pins unaltered.
Photos under : the back of the amp and the connector/adapter.
Observations...
Second, I have to point out that all channels outputs are connected to six 8 ohms load resistors, one for each channel.
To evaluate noise, I just use my ears : so one tweeter is paralleled with resistor on one channel and one tweeter+one woofer on the other, each one paralleled on two resitors.
By the way the tweeter is stuck to my ear and I have to shut-off my computer and other stuff to have complete silence for perfect assessment.
Let's go!
1) If I connect one of the 6Pins/adapter on only one channel, no noise added at all.
2) If I connect the other channel only, the same way, no noise added at all, again.
3) If I connect both connectors/adapters in both channel, a very very very small buzz added, barely perceptible with tweeter stuck to the ear and like this, it would be definitely acceptable for me and I would almost say...for a lllllot of people!
This is the situation for grounds right now.
Now, let's put the signal pins in the picture...by shorting all pins together on each of the two connector/adpaters.
1) If I connect only one connectors/adapter to one channel, now noise can be heard from 4 inches...unacceptable.
2) Same thing for the other channel.
3) If i connect the two connectors/adapters to the two channels, noise increases by a good 10 dB! Bad. Very bad!
So?
Luke
An observation to show.
First I built a cable adapter which uses a pair of the matching Neutrik male connectors to fit into the actual amp.
On each connector pins 1,3 & 5 which are negatives or Gnd contacts are all connected together.
And the two connectors are connected together by these common connections.
That means six grounds brought together but the six signal pins unaltered.
Photos under : the back of the amp and the connector/adapter.
An externally hosted image should be here but it was not working when we last tested it.
Observations...
Second, I have to point out that all channels outputs are connected to six 8 ohms load resistors, one for each channel.
To evaluate noise, I just use my ears : so one tweeter is paralleled with resistor on one channel and one tweeter+one woofer on the other, each one paralleled on two resitors.
By the way the tweeter is stuck to my ear and I have to shut-off my computer and other stuff to have complete silence for perfect assessment.
Let's go!
1) If I connect one of the 6Pins/adapter on only one channel, no noise added at all.
2) If I connect the other channel only, the same way, no noise added at all, again.
3) If I connect both connectors/adapters in both channel, a very very very small buzz added, barely perceptible with tweeter stuck to the ear and like this, it would be definitely acceptable for me and I would almost say...for a lllllot of people!
This is the situation for grounds right now.
Now, let's put the signal pins in the picture...by shorting all pins together on each of the two connector/adpaters.
1) If I connect only one connectors/adapter to one channel, now noise can be heard from 4 inches...unacceptable.
2) Same thing for the other channel.
3) If i connect the two connectors/adapters to the two channels, noise increases by a good 10 dB! Bad. Very bad!
So?
Luke
Last edited:
late to the thread - but how can any help without more info?
did I miss the amp module names, schematics?
is there a relay board - input or output switching?
are the 3 PS toroid xfmrs?
where's your wiring diagram?
sorry if I missed these - but everyone is shooting in the dark without more internal photos showing ps parts mounting wire routing....
"big hammer" solutions may exist either in heavy gnd bus/bars or electronic signal side isolation or balanced transmitter/receivers to break common gnd noise coupling and/or loops
did I miss the amp module names, schematics?
is there a relay board - input or output switching?
are the 3 PS toroid xfmrs?
where's your wiring diagram?
sorry if I missed these - but everyone is shooting in the dark without more internal photos showing ps parts mounting wire routing....
"big hammer" solutions may exist either in heavy gnd bus/bars or electronic signal side isolation or balanced transmitter/receivers to break common gnd noise coupling and/or loops
Hello JCX
To anser your three questions...
1) Circuit is Avondale NCC200, slightly modified to suit my needs.
Here is the SCH.
An externally hosted image should be here but it was not working when we last tested it.
2) There is a relay circuit for speaker on/off delayed switching and it's fed by one of the 29.5Vac coil for MainPSU. Circuit produces Vdc to activate 24Vdc coils that gets grounded by transistor switching according to a delay controlled by a time constant. Simple circuit. It's totally floating because it drives the relay coils only. Ground only exists for grounding relay's coils.
3)One toroid, 2 coils 59Vac/15 amps and 2 other coils 79Vac/0.25amp.
Luke
but burning resistors when connecting all the "gnds" isn't pretty
definitely check for xmfr winding shorts - simple leakage currents shouldn't be above mA
internal to the PS boards there can be issues - the "proper" gnd takeoff point is after windings and bridge currents are summed - the "point" between the +,- reservoir caps gnd pins - its not the CT/join of the windings
the amp output Zobel can't be expected to work well through off board wiring - should be to local, high frequency bypassed amp pcb gnd - which may not exist - looks like the output stage is just waving in the wind at the end of whatever PS wiring - not good
some hype is expected - but to claim that's a carefully tweaked layout?
definitely check for xmfr winding shorts - simple leakage currents shouldn't be above mA
internal to the PS boards there can be issues - the "proper" gnd takeoff point is after windings and bridge currents are summed - the "point" between the +,- reservoir caps gnd pins - its not the CT/join of the windings
the amp output Zobel can't be expected to work well through off board wiring - should be to local, high frequency bypassed amp pcb gnd - which may not exist - looks like the output stage is just waving in the wind at the end of whatever PS wiring - not good
some hype is expected - but to claim that's a carefully tweaked layout?
Last edited:
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.